While everyone is used to haggling over big-ticket items like a house or a car, this tough economy is presenting opportunities to negotiate a better price on everything from hotel stays to flat-screen TVs to shoes to cell phone service. Check out the principles of successful haggling and how to put them into play.

Purchasing power

The golden rule of haggling is that people will not negotiate unless they think you can either help them or hurt them, states Roger J. Volkema, a professor at American University and author of “The Negotiation Toolkit.” When it comes to haggling with retailers or hotels or service providers, he says, you can help or hurt them by taking your business elsewhere. Keep that in mind as you set out on your haggling adventures, he counsels.

Don't be afraid to ask

Never assume the price you see is the price you have to pay. “You are entitled to pursue your interests, and your interest is getting the best stuff at the best price,” said Steven P. Cohen, president of The Negotiation Skills Company Inc. in Massachusetts. The old adage is true: The worst that can happen is that they can say no.

Be prepared

Although it never hurts to ask, haggling success directly correlates to the amount of research you've done before you start negotiations. You need to know what others retailers are charging for a particular product. You might even want to bring in ads or printouts of lower prices because most stores price match.

Check out release dates for new products. If new models are coming out soon, a store will be more inclined to slash prices on its current inventory. Look for closeout sales, says Rick Doble, co-author of “Cheaper: Insider Tips for Saving on Everything,” because stores want to move those items quickly. Floor or display items are always a good target for getting what you want at a lower price.

Get a read on the situation

Even in this economy, you can't haggle on anything and everything. You can get a good sense of whether a store will budge on price by how the salespeople behave toward you, Cohen says. “Suss out what leverage you have,” he recommends. “Reading their body language is key. If you go into a store where the clerks are all over you, you have a good chance to haggle versus a store where no one will give you the time of day.”

Talk to the right person

Oftentimes salesclerks don't have the authority to wiggle on price. “A very safe and fair question to ask is 'Can you and I discuss price?' ” Cohen recommends. If a salesperson says no, then ask to speak to the manager.

Also, people working the cash register might have extra coupons on hand or might know of special deals, so ask them as you check out. For instance, Macy's has a program at select stores that knocks off 11 percent from your purchases if you are visiting from another location.